<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>ajax取消请求</title>
</head>
<body>
    <button>发送请求</button>
    <button>取消请求</button>
    <script>
        const btns = document.querySelectorAll('button');
        let xhr = null;
        btns[0].onclick = function(){
            xhr = new XMLHttpRequest();
            xhr.open('GET', 'http://localhost:8000/delay');
            xhr.send();
            xhr.onreadystatechange = function(){
                if(xhr.readyState === 4){
                    if(xhr.status >= 200 && xhr.status < 300){
                        console.log(xhr.response)
                    }
                }
            }
        }
        btns[1].onclick = function(){
            //abort取消请求
            xhr.abort();
        }
    </script>
</body>
</html>